And Football Federation Australia appears willing to at least have a "discussion" around whether it will tip in the $900,000 required to get the ambitious proposal off the ground.

Australian football agent Tony Rallis says an in-principle deal has been reached to bring the eight-time Olympic gold medallist to Central Coast for a six-week trial.

Simms, who signed Bolt when he was a 15-year-old prodigy, said it was a genuine possibility.

"Usain has made it quite clear that he's interested in playing professional football," Simms told AAP.

"We're looking at a number of options and this is one of them."

Bolt, 31, retired from sprinting last year but is a lifelong football fan and has long harboured ambitions of playing.

But there are serious doubts he could pass muster as a professional - even at the Mariners, who finished bottom of the A-League table last season.

Bolt has trained or trialled at numerous clubs around the world, including Germany's Borussia Dortmund, South Africa's Mamelodi Sundowns, and Norway's Stromsgodset.

None have seen fit to offer him a fulltime deal.

Rallis told AAP that Bolt's trial would only go ahead if FFA agreed to contribute funds towards his contract if he is successful.

"(Simms) understands it," Rallis told AAP.

"We're not going to risk the Bolt image or brand or discredit the A-League.

"It's a trial, no different to Jarryd Hayne in the NFL, or rugby league players becoming boxers or AFL players.

"We're going through the proper channels; we're just waiting for a reply."

FFA has a pot of $3 million, provided by Fox Sports, to spend on marquee players for the upcoming season.

FFA is believed to be deep in talks with former Japanese international Keisuke Honda, who is interested in joining Melbourne Victory and would command the majority of the fund if he reaches an agreement with the A-League champions.

Conceivably, the rest could be allocated to Bolt - and then freed up to be spent on other players if he does not win a contract.

"We are actively working with A-League clubs on a number of potential marquee players," an FFA spokesperson told AAP.

"While Usain Bolt is one of the most famous athletes on the planet, he's not a professional footballer.

"If the trial goes ahead and Central Coast Mariners decide it stacks up and they want to offer him a contract, then we will have a discussion with them around that and what might be possible."

The news has been met with a decidedly mixed reaction.

Some believe it will give the A-League a pang of much-needed publicity.

Others, like Fox Sports commentator Simon Hill, believe it reduces the competition to a "a sideshow, a circus freak show, a gimmick."

"We don't need it," Hill told SEN Radio.

"If we are going to bring in big stars, then let's get proper marquee players, for which you have to pay."